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Topic: Original AC oil filter date codes (Read 11126 times)

Does anyone know how to decode the date code on original AC oil filters? I've seen one with the date code "CJ22" in light blue screen print ink ( same color as other text) on the side. Is the "C" for Chevrolet? Is the letter "J" for the month begininng in January or the model year? Did the months skip the letter "I"? I assume the "22" is the 22nd day of whichever month is applicable.

Does anyone know how to decode the date code on original AC oil filters? I've seen one with the date code "CJ22" in light blue screen print ink ( same color as other text) on the side. Is the "C" for Chevrolet? Is the letter "J" for the month begininng in January or the model year? Did the months skip the letter "I"? I assume the "22" is the 22nd day of whichever month is applicable.

A friend of mine worked at AC Engineering, and was a supervisor on the filter line for several years; I'll bounce this past him and see what he says, and post his response.

Here's Don's response - he has conducted many NCRS Tech Sessions on AC oil filters, and has hundreds of them in his collection; do you have photos of the filter?

Pf-25's were painted white with blue silkscreening until mid-1974 with no date codes Pf-25's were painted blue with paper/foil labels from late 1974 to early 1976 with no date codes Pf-25's were painted blue with paper labels starting in mid-1976 with no date codes at least through 1982. The first examples I have of what may be date codes are PF-25's in replacement AC-Delco boxes as follows: Carton Date: 6-97 Code on filter: 274702 Could be: 274th day of 1997 2nd shift Carton Date: 9-97 Code on filter: 349702 Could be: 349th day of 1997 2nd shift Carton date: 8-01 Code on filter: 111J2 No idea what this means but believe they were made by a different manufacturer because the round emboss on the shell is smaller than the original filter

I also believe the 1969 Camaro from the factory had an emboss message on the end of the shell that was removed later.To complicate things further, a version of the PF-25 was produced in Canada that had different silkscreening.

I would like to see pictures or a description of the filter in question.

Attached is another NOS PF-29 oil filter (6437946), but a different can design than the previous one I posted. I don't have the date code data on this one.

From what I read about the PF-29 oil filter in the Camaro Master Parts Manuals, it was the original factory oil filter for 1968 Camaros with V8 engines. The PF-25 oil filter (6438261) superseded the PF-29 filter and was available at least through 1973, if not later (one of my two Master Parts Manuals ends in July 1969, the other one ends in 1973).

My theory on the date code is that the model year was used, not the calendar year. I arrived at this conclusion because the carton for the PF-29 oil filter only listed 1968 V8 engines...no other years. Assuming that the 1968 model year began in August 1967, here's how I decode "CJ22" on the filter:

"C" = Chevrolet."J" = April 1968 (if Letter "I" was skipped) or May 1968 (if Letter "I" was not skipped)."22" = 22nd day of month.

I can't explain the two different PF-29 filters, though. Maybe one was a Canadian version?

I have no idea what the code represents. N is the 14th letter ( or 13th if the I is not used)so it can't represent a month. In all my years at AC I don't recallusing a silkscreen for date coding a product."